This invention relates to the generation of stereoscopic video imagery, and more particularly to an optical system in which imagery from moving photographic film is displayed in stereoscopic video form.
For the training of personnel, it is often desirable to simulate a view of the terrain as viewed in flight. The simulation of stereoscopic video is of use in system design and operator training for obstacle detection, reconnaissance, and aerial refueling tasks.
Prior approaches to generating stereo video are based on using two input channels (i.e. two cameras or two recorders) and preclude interaction with the generated imagery. There also may be annoying display flicker.
Computer generated imagery is commonly perceived as being totally artificial (cartoonish), and it is not known to have been done in stereo. It is extremely expensive to produce.
Terrain boards or belts are now used for simulation. Stereo would require dual television systems, and would be difficult and expensive. It could not be accomplished with a single optical probe. There is no parallax. A system would require two cameras and two video channels.
There are many known systems for generating stereoscopic displays, which include means to control geometric distortions and other factors. For example, Pat. No. 3,564,133 teaches a method for transforming the scanning raster of a flying spot scanner to correct for distortion with respect to a reference of an image being scanned by the scanner. Pat. No. 3,595,995 discloses an improved method for establishing complex high order transformations which are necessary when correlating stereo photographs of rough terrain. Pat. No. 3,705,261 shows a system for exposing a pair of visual read-outs or photographs which can be viewed as a stereoscopic image of an object. Pat. No. 3,860,752 teaches a virtual image viewing system which includes a flying spot scanning means that is responsive to deflection signals and also receives a laser beam for deflecting the beam in two dimensions and for converging the beam to form an unmodulated flying spot raster. Pat. No. 3,912,856 shows a three-dimensional image transmitting apparatus comprising a scanning beam which scans a subject and reflects therefrom, and a signal screen which generates an electrical location signal that corresponds with the location of incidence of the reflected beam on the screen, the contour of the scanned subject being formed on the screen, and electrical signals corresponding to the contour being transmitted to a device for reconstructing a three-dimensional image of the subject.
The strip camera was an important breakthrough in aerial photography in the late 1930's. Its early development and some of its history is noted in a book by George W. Goddard, et al, "Overview, A Life-Long Adventure in Aerial Photography" (Doubleday & Company, Inc., Garden City, N.Y. 1969) starting at pages 241-244. On page 243 it is noted that Andy Matos developed a most valuable feature by using twin lenses to produce stereoscopic photographs in black and white and color. The strip camera does not use a shutter. The camera takes a continuous panoramic picture, the film moving across a long, narrow open slit in the center of the focal plane. The long dimension of the slit is perpendicular to the line of flight. The design concept depends on the speed of the film moving past the camera focal plane governed by the aircraft speed, its altitude, and the focal length of the camera lens. It is important to synchronize the film's movement with the movement of the image in the camera. In current stereoscopic strip cameras, two lenses are fixed relative to one another, with a tilt of, typically, seven degrees between them.